Fireproof varnish



GR 195999026. i

UNITED STATES PATENT OFFICE.

CECIL L. SAUNDERS, GEORGE C. STANLEY, AND CHARLES W. BENNETT, OF ITHAOA,NEW YORK.

FIREPBOOF VARNISH.

Specification of Letters Patent.

Patented Dec. 6, 1921.

N0 Drawing. Original application filed October 13, 1919, Serial No.330,384. Divided and this application filed November 3, 1920. Serial No.421,525.

To all whom it may concern:

Be it known that we, CEoIL L. SAUNDERS, GEORGE G. STANLEY, and CHARLEsW. BEN- NETT, all citizens of the United States, each residing at Ithacain the county of Tompkins and State of New York, have invented certainnew and useful Improvements in Fireproof Varnish; and we do herebycleclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to a composition of matter in the form of anemulsified varnish which is applicable to the fire proofing of fabricsin general, and especially the fire proofing of aeroplane wings. I

The object of the invention is to provide a composition or emulsifiedvarnish which is less costly, and more efficient in use than thoseheretofore proposed.

With this and other objects in view the invention consists in the novelcomposition of matter, or emulsified varnish, all as will be more fullyhereinafter disclosed and particularly pointed out in the claims.

This application is a division of our copending application Serial No.330,384, filed October 13, 1919, and entitled Composition of matter andprocess of producing the same.

In order that the precise invention may be the more clearly understood,it is said 5-- It is well known that the fabrics from which aeroplanewings are produced are often subjected to fire risks, and that it isvery desirable indeed to so fire proof said fabrics without destroyingtheir strength that should they become ignited, the flame will notspread and the aviator may thereupon reach a landing in safety. It isalso well known that it is very desirable to coat fabrics in generalwith a fire proofing material, having the above mentionedcharacteristics, but to all of the materials and methods with which weare acquainted, various objections exist.

That is to say, prior processes either rot the fabrics, or the flameswill spread unduly, or it is so expensive to apply the coating that theyhave not proved satisfactory in service. Especially has it been found inthe prior processes that the fire proofing coating, whatever it may be,is easily Washed out, so that after the fabric has been subectedtoserious wettings, its fire proofing qualities are greatlydeteriorated.

Further, it has been found in practice that it is a very diflicultmatter indeed to so open up the fibers of the material that the fireproofing substances will thoroughly penetrate the same.

In the invention, now to be described, all the above objections are doneaway with, as will presently appear. That is to say, as stated in oursaid copending application, above mentioned, we have discovered thatalthough hydrofluoric acid will readily destroy the fibers of fabrics ingeneral, yet, if a fabric such as cotton is first boiled in water, toremove the size, and then treated with a Weak solution of hydrofluoricacid, say about two parts in one hundred parts of water, as by dippingthe said fabric for thirty minutes in the solution, and if it is thenwashed, and brought to a semi-dry state, the fabric will be found not tobe 3 weakened at all, but even strengthened to a {I degree. 5' 0 Itspores will also be found to be so open that it will readily take thefire proofing solution, about to be described.

After the above mentioned treatment with hydrofluoric acid, we next maypass the fabric through a solution of sodium stannate, preferably havinga specific gravity of 1.075. The fabric is subjected to this lastmentioned solution for about say one half minute, or somewhat longer,whereupon it is wrung out and dried. We then pass the said fabricthrough a solution of ammonium sulfate, preferably having a specificgravity of about 1.045 and it is subjected to this last mentionedsolution for about the same time as just stated, or about say one minuteor a little longer.

The fabric is now taken out of this am; e solution whereupon itmay bewrung out and dried, or it may be washed with water and dried. Thefibers of the fabrio, if closely examined will be found to be coagedwith hydrated oxid of tin or stannic aci The reaction may be stated asfollows This said hydrated oxid of tin SnO a'I-I O ages is in anexceedingly finely sub-divided condition, and it functions as a mostefficient fire proofing material or agent for preventing the spreadingof flame, Whether it be applied to fabrics, to the fibers before thefabrics are made up, or even to Wood. Whereas, the above treatment isfound to be efiicient in practice, our preferred process consists in thefollowing We take a mixture of sodium stannate and of ammonium sulfate,as above mentioned, but preferably in the solid condition, and grindthem together until the fumes of ammonia come off, whereupon we add tothe mixture any suitable varnish. This old or well known. varnish may beof a gummy or resinous nature, or it may be the well known varnish thatis now used on aeroplane wings, which is a cellulose nitrate, or acellulose acetate. After the ordinary varnish is thus mixed with theabove reagents, the grinding is continued until we have produced athorough and intimate mixture of the said ordinary varnish, and thehydrated tin oxid that is produced by the reaction during the grindingoperation.

As this reaction cannot, under the circumstances be a complete reaction,the ordinary varnish will be thus emulsified, or intimately mixed, notonly with the hydrated tin oxid, above mentioned, but there will also bepresent some ammonium sulfate, as well as some sodium stannate, andundoubtedly some sodium sulfate too, each of which ingredients are goodfire proofing reagents. The presence of the ammonium ion undoubtedly hasa good effect in causing a thorough incorporation of the hydrated tinoxid into the fibers of the fabric when'th-e varnish con-- taining saidingredients is applied thereto.

Especially will this incorporation be very thorough if the fabric hasbeen previously treated with the hydrofluoric acid solution abovementioned.

The varnish, whether it be a resinous one or one having a cellulosebase, after being thus emusified, so to speak, with the fire proofingsubstances, above mentioned, constitutes an article'of commerce initself, and We wish it to be distinctly understood that this inventioncomprising said emulsified varnish relates broadly to such a compositionno matter to what substances it may be applied. Further, although thissaid emulsified varnish may be made by other processes, than thatmentioned, yet, we prefer to produce the emulsified varnish in themanner above disclosed because it is an efficient way to impart intoordinary varnish a number of fire proofing agents Which serve, togetherwith the former treatment of the fibers, to so thoroughly impregnate thelatter that in practice, the product is found to resist fire to a degreemuch higher than those produced by other methods with which we areacquainted.

It is obvious that those skilled in the art may vary the composition ofthe product without departing from the spirit of the invention, andtherefore, we do not Wish to be limited to the above disclosure exceptas may be required by the claims.

WVhat We claim is 1. A fireproof coating composition comprising varnishhaving intimately incorporated therein a hydrated oxid of tin,substantially as described.

2. A fireproof coating composition comprising varnish having intimatelyincorporated therein a hydrated oxid of tin and sodium stannate,substantially as described.

3. A fireproof coating composition comprising varnish containing in anemulsified form substantial percentages of a hydrated oxid of tin,sodium stannate, and ammonium sulfate, substantially as described.

In testimony whereof we affix our signatures.

CECIL L. SAUNDERS. GEORGE C. STANLEY. CHARLES W. BENNETT.

